@@ -199,6 +199,50 @@ Advanced
199199 option is enabled, a namespace operation may complete before the MDS
200200 replies, if it has sufficient capabilities to do so.
201201
202+ :command: `crush_location=x `
203+ Specify the location of the client in terms of CRUSH hierarchy (since 5.8).
204+ This is a set of key-value pairs separated from each other by '|', with
205+ keys separated from values by ':'. Note that ' |' may need to be quoted
206+ or escaped to avoid it being interpreted as a pipe by the shell. The key
207+ is the bucket type name (e.g. rack, datacenter or region with default
208+ bucket types) and the value is the bucket name. For example, to indicate
209+ that the client is local to rack "myrack", data center "mydc" and region
210+ "myregion"::
211+
212+ crush_location=rack:myrack|datacenter:mydc|region:myregion
213+
214+ Each key-value pair stands on its own: "myrack" doesn't need to reside in
215+ "mydc", which in turn doesn't need to reside in "myregion". The location
216+ is not a path to the root of the hierarchy but rather a set of nodes that
217+ are matched independently. "Multipath" locations are supported, so it is
218+ possible to indicate locality for multiple parallel hierarchies::
219+
220+ crush_location=rack:myrack1|rack:myrack2|datacenter:mydc
221+
222+
223+ :command: `read_from_replica=<no|balance|localize> `
224+ - ``no ``: Disable replica reads, always pick the primary OSD (since 5.8, default).
225+
226+ - ``balance ``: When a replicated pool receives a read request, pick a random
227+ OSD from the PG's acting set to serve it (since 5.8).
228+
229+ This mode is safe for general use only since Octopus (i.e. after "ceph osd
230+ require-osd-release octopus"). Otherwise it should be limited to read-only
231+ workloads such as snapshots.
232+
233+ - ``localize ``: When a replicated pool receives a read request, pick the most
234+ local OSD to serve it (since 5.8). The locality metric is calculated against
235+ the location of the client given with crush_location; a match with the
236+ lowest-valued bucket type wins. For example, an OSD in a matching rack
237+ is closer than an OSD in a matching data center, which in turn is closer
238+ than an OSD in a matching region.
239+
240+ This mode is safe for general use only since Octopus (i.e. after "ceph osd
241+ require-osd-release octopus"). Otherwise it should be limited to read-only
242+ workloads such as snapshots.
243+
244+
245+
202246Examples
203247========
204248
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